Stereotype plate



- July 5, 1949. c. s. CRAFTS sTEREoTYPE PLATE Filed June 13, 1945' Patented July 5, 1949 STEREOTYPE PLATE -Curtis S. Crafts, Oak Park, Ill., assignor to The Goss Printing Press Company, Chicago, Ill., a corporation of Illinois Application June 13, 1945, Serial No. 599,229

The present invention pertains to curved stereotype plates, and more particularly to plates adapted for use in a so-called tension lookup. In Such a lookup, the plate is tensioned circumferentially of the print cylinder to hold it in place. For further detail of the locking devices and cylinders used with plates embodying the present invention, reference may conveniently be made to my article entitled New lockup published in the March 1945 issue of Printing Equipment Engineer, pages 11 to 15.

One object of the present invention is to provide a stereotype plate adapted for use in a tension lookup and which is of a novel construction such as to withstand in a superior manner the severe punishment to which such a plate is subjected during high speed press operation.

Another object is to provide such a plate which is laid out in a manner to minimize shrinks, weak spots or other faults in casting it.

Further objects and advantages of the invention will become apparent as the following description proceeds, taken in connection with the accompanying drawings, in which:

Figure 1 is a perspective view of a curved stereotype plate embodying the present invention.

Fig. 2 is an enlarged fragmentary face view of a portion of the inner or concave face of the plate shown in Fig. 1.

Figs. 3 and 4 are enlarged detail sectional views taken respectively substantially along the lines 3-3 and ll-ll in Fig. 2.

Fig. 5 is a detail sectional view, on even larger scale, taken substantially along the line 5 5 in Fig. 2.

While the invention is susceptible of various modications and alternative constructions, I have shown in the drawings and will herein describe in detail the preferred embodiment, but it is to be understood that I do not thereby intend to limit the invention to the specific form disclosed, but intend to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claim.

Referring more particularly to the drawings, I have shown in Fig. 1 a curved stereotype plate embodying the present invention. As is customary in stereotype plates, it is cast from stereotype metal and is of semicylindrical overall shape. On its convex or outer surface is the design or reproduction of type (not shown) which is to be printed.

In the concave or inner face of the plate are two longitudinally extending rows of pockets l0,

1 Claim. (Cl. 101-378) adjacent the leading and trailing edges of the plate, and in which are received suitable tension ngers (not shown). Such fingers pull the plate tightly and solidly about a printing cylinder to which it is applied, all as more particularly described in my article in Printing Equipment Engineer identified above. These pockets I0 are desirably undercut by a slight inclination of their bottom walls ll (Figs. 3 and 5) to insure a rm grip for the fingers inserted in them. By inclining these bottom walls I0 at a small angle (for example, of the order of 15 degrees) to a plane normal to the vertical medial plane of symmetry of the plate, the pressure of the retaining iingers on the pocket bottoms I0 gives a component of force in a direction such as to pull the plate edges inward and seat them rmly against the cylinder.

The pockets l0 are either cored or milled directly into the body of the plate since the entire concave surface of the latter should preferably be a surface of revolution, free of inward projections, to insure proper seating on the printing cylinder. Such being the case, the plate is of minimum thickness in the portion overlying the pockets. These relatively thin portions of the plate are a source of potential weakness, particularly in View of the heavy loading imposed by the impact of impression.

I have found that the pockets Ill can be adequately reinforced, to withstand even the heavy loads to which the portions of the plate defining them are subjected, by contouring their rear or inner walls l2 in smoothly arched form. As illustrated, the rear walls I2 are arched in all planes of longitudinal section. Such form enables them to withstand a maximum moment of bending.

The arched shape of the pockets I0 is additionally desirable in that it is especially well suited to formation either by coring or milling. In oase the pockets are cored out during the original casting of the plate, the rounded or curved shape of the pocket ends prevents formation of blow holes and imperfections in the casting which result if square ends are used. If the pockets are, on the other hand, machined after casting, the illustrated shape is such that they can each be readily out by a single pass of a rotary form cutter of suitable shape.

The outer edges of the pockets I0 are beveled or relieved as indicated at I4 (see particularly Figs. 4 and 5). This is an important feature for several reasons. N ot only does it prevent the throwing up of a burr which would interfere with proper seating of the plate on the cylinder, but in addition the beveling prevents a distortion o! the pocket edges under the high unit pressures developed by the gripping fingers.

The portions of the plate lying between the pockets I and the leading and trailing edges of the plate are solid to afford maximum strength in such areas since that is the portion of the plate acted directly upon by the tension ngers. For the sake of simplicity, the entire leading and trailing edge portions I of the plate are in this instance made solid from end-to-end of the plate, thus constituting in eect heavy integral bars over which the tensioning ngers inserted in the pockets are hooked,

The concave face of the plate lying between the marginal or bar portions I5 is cored out to dene a plurality of parallel circumferentially extending grooves I6. Such grooves are separated by circumferential bearer ribs II intersected at intervals by longitudinally extending bearer ribs I8. Both the ribs I1 and I8 are of tapered cross section and have top surfaces which are flat in sectional prole. The top surfaces of the ribs I'I, I8 as well as the marginal portions I5 of the plate all lie in a common surface of revolution centered on a longitudinal axis corresponding in location to the axis of the cylinder to which the plate is to be applied. In making the plate, it is preferably interiorly machined to form the top surfaces of the ribs and marginal portions I5, al1 of which bear directly against the cylinder periphery.

The relative dimensioning of the ribs I'I, I8 is of some consequence in minimizing shrink spots during casting. By way of suitable example, of dimensions it may be noted that for a standard {'s inch thick newspaper stereotype plate, the circumferential ribs I1 may be M3 of an inch wide at the top and have anks or side faces sloped at 45 degrees, the spacing between ribs being approximately 3%4 of an inch. The longitudinal ribs I8 on the other hand may be spaced at intervals of 221/2 degrees and have top faces of a maximum width of 13% of an inch, their anks also being sloped at 45 degrees.

The ends of the groove I6 are, as indicated at I9, sloped gently upward toward the outer faces of the marginal or bar portions I5 of the plate. It is in these sloped end walls or faces I9 of the grooves that the pockets III are located, each pocket extending across the ends of a plurality of grooves and intervening ribs I1. Intermediate successive pockets I0 are the end portions of at least one of the ribs I1. c By thus, in effect, merging the pockets and ribbing, the liability of shrink spots adjacent the pockets is minimized. In that connection it will be understood that abrupt changes in cross section of the plate always entail a maximum liability of shrinkage difficulties.

I claim as my invention:

A curved stereotype printing plate adapted to be tensioned circumferentially about a cylinder, said plate having a plurality of pockets in its concave surface for the reception of gripper ngers, said pockets being arranged in two series adjacent respective leading and trailing edges of the plate, all of said pockets being elongated in the longitudinal direction and having a smoothly arched contour both longitudinally and circumferentially of the plate, said pockets being undercut with the bottom walls of the pockets inclined at a small angle of the order of fteen degrees with reference to a plane normal to the medial plane of symmetry of the plate, and said plate being solid between the bottoms of said pockets and immediately adjacent portions of its leading and trailing edges.

CURTIS S. CRAFTS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,932,357 Styri Oct. 24, 1933 1,942,408 Bruerhaber Jan. 9, 1934 2,038,104 Fuller Apr. 21, 1936 2,047,357 Crafts July 14, 1936 2,131,891 Huck Oct. 4, 1938 2.180,732 Durham Nov. 21, 1939 

